neurons within the brain and spinal cord

The surface of the brain is covered with gyri and sulci. The most prominent sulcus, known as the longitudinal fissure, is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.įigure 1. These gyri and sulci form important landmarks that allow us to separate the brain into functional centers. The surface of the brain, known as the cerebral cortex, is very uneven, characterized by a distinctive pattern of folds or bumps, known as gyri (singular: gyrus), and grooves, known as sulci (singular: sulcus), shown in Figure 1. In the opposite direction, the spinal cord ends just below the ribs-contrary to what we might expect, it does not extend all the way to the base of the spine. The top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such as breathing and digestion. It not only routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes. The spinal cord is like a relay station, but a very smart one. It can be said that the spinal cord is what connects the brain to the outside world. In this section, we discuss the overall organization of the brain and the functions associated with different brain areas, beginning with what can be seen as an extension of the brain, the spinal cord. Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors. It is a bilateral, or two-sided, structure that can be separated into distinct lobes. The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. Here we will focus on the central nervous system, with particular emphasis on the brain and its role in complex thought. The nervous system is divided into two main parts – the central nervous system, made up of the brain and spinal cord, and the peripheral nervous system, which includes all other parts of the nervous system.

Neurons within the brain and spinal cord